This chapter describes the existing environment that could be affected by actions proposed in the East Yosemite Valley Utilities Improvement Plan. Topics considered were selected based on federal law, regulations, executive orders, NPS Management Policies, National Park Service subject matter expertise, and concerns expressed by other agencies or members of the public during scoping and comment periods. The conditions described establish the baseline for the analyses of effects found in Chapter IV, Environmental Consequences.

Resource Topics Considered in this Environmental Assessment

Natural Resources

The federal and state Endangered Species Acts (and associated legislation), Clean Water Act, Clean Air Act, and National Environmental Policy Act (NEPA) require that the effects of any federal undertaking on natural resources be examined. The Wild and Scenic Rivers Act specifies guidelines for the determination of appropriate actions within the bed and banks of a Wild and Scenic River and requires managing agencies to determine whether water resources projects would adversely affect free flow or Outstandingly Remarkable Values.  In addition, National Park Service management policies and natural resource management guidelines call for the consideration of natural resources in planning proposals. Yosemite Valley is an area of abundant natural resources and contains stretches of the Merced River which are designated as wild and scenic. It is therefore necessary to characterize both these natural resources and the environmental consequences to these resources that could result from implementation of the East Yosemite Valley Utilities Improvement Plan alternatives. Analysis was performed for the following natural resource topics: soils; hydrology, floodplains, and water quality; wetlands; vegetation; wildlife; special-status species; air quality; and noise.  An assessment of the potential effects on the free flow and Outstandingly Remarkable Values was also performed.

Cultural Resources

The National Historic Preservation Act, the Archeological Resources Protection Act, Native American Graves Protection and Repatriation Act (NAGPRA), and the NEPA require that the effects of any federal undertaking on cultural resources be examined. In addition, National Park Service management policies and cultural resource management guidelines call for the consideration of cultural resources in planning proposals. Significant cultural resources exist within the project area and adjacent areas and could be affected by the alternatives. Therefore, analysis was performed for archeological resources, traditional cultural resources, and cultural landscape resources, including historic sites and structures.

Social Resources

The analysis of social resources examines the effects of the East Yosemite Valley Utilities Improvement Plan on the social environment within the park. Conserving the park’s scenery is a crucial component of the National Park Service 1916 Organic Act and the park’s enabling legislation. Stewardship of Yosemite National Park requires consideration of two integrated purposes: to preserve Yosemite’s unique natural and cultural resources and scenic beauty, and to make these resources available to visitors for study, enjoyment, and recreation. Resources analyzed and addressed include scenic resources, recreation, park operations and facilities, and socioeconomics.

Impact Topics Dismissed From Further Analysis

Environmental Justice

No aspect of the action alternatives of the East Yosemite Valley Utilities Improvement Plan would result in disproportionately high and adverse human health or environmental effects on minority or low-income populations. Any restriction on travel or access to any area of the park that might result from implementation of the East Yosemite Valley Utilities Improvement Plan would be equally applied to all visitors, regardless of race or socioeconomic standing. As well, none of the action alternatives would change current management direction concerning housing policy in Yosemite National Park, El Portal, or other areas adjacent to the park. Policies concerning the future availability of housing in these areas are already in place and would not change as a result of the East Yosemite Valley Utilities Improvement Plan. Therefore, the action alternatives would not result in destruction or disruption of community cohesion and economic vitality; displacement of public and private facilities and services; increased traffic congestion; and/or exclusion or separation of minority or low-income populations from the broader community.

Natural Resources

Geology and Geologic Hazards
 

There are no potential effects to geology or geologic hazards related to any of the proposed actions. 

 

Prime and Unique Agricultural Lands

There are no known agricultural lands in the project area, and the proposed action would not have any indirect effects to downstream agricultural lands.

Wilderness Experience

There is no designated Wilderness within the project area. Implementation of the proposed action would not have any direct or indirect effects to designated Wilderness in adjacent areas.

Social Resources

Land Use

Land uses within Yosemite National Park are classified as “Parklands,” regardless of the individual types of land uses within the park. Implementation of the East Yosemite Valley Utilities Improvement Plan would not affect Parkland land uses within the park.

Museum Collection

Implementation of the East Yosemite Valley Utilities Improvement Plan could indirectly affect the museum collections by generating minimal additions to the collections due to archeological data recovery performed as mitigation for direct site impacts. Such additions would require museum storage space and ongoing collection maintenance and management.

Regional Setting

Yosemite National Park lies on the western slope of the Sierra Nevada, a massive mountain range dividing central and northern California from more arid lands to the east. The Sierra Nevada ecoregion (which extends through the foothill zone on the west side and the base of the escarpment on the east side) is about 450 miles long and 100 miles wide. Elevations in the park range from approximately 2,000 feet to 13,114 feet. Most of the 747,969 acres of the park is designated Wilderness (94%, or 704,624 acres).

The Merced River flows from the headwaters in the high elevations of the Sierra Nevada, through Yosemite Valley, and down to the San Joaquin Valley, where it contributes to the San Joaquin River. The Merced River contains separate and unique watersheds, sustains separate hydrologic and aquatic resources, and supports differing levels of development. The main stem of the Merced River drains approximately 250,000 acres from the headwaters within the park to the Foresta Bridge in the El Portal area. The main stem of the Merced River flows a total of 140 miles from its headwaters to its confluence with the San Joaquin River. The South Fork drains the southern portion of the park, an area of approximately 76,000 acres. The Tuolumne River drains the northern portion of the park, an area of approximately 435,000 acres.

The major vegetation zones of the Sierra Nevada form readily apparent, large-scale north-south elevational bands along the axis of the mountain range. Major east-west watersheds that dissect the Sierra Nevada with steep canyons form a secondary pattern of vegetation. On the west side, forest types change with increasing elevation from ponderosa pine to mixed conifer to firs. Straddling the crest of the Sierra Nevada is a zone of subalpine and alpine vegetation. Fire suppression, in concert with changing land-use practices, has changed natural fire regimes of the Sierra Nevada dramatically. This has altered ecological structures and functions in Sierra Nevada plant communities (UC Davis 1996). Aquatic and riparian systems are the most altered and impaired habitats of the Sierra Nevada. Foothill areas below about 3,300 feet appear to have the greatest loss of riparian vegetation of any region in the Sierra Nevada (UC Davis 1996).

Recreational opportunities abound in Yosemite National Park in developed and wilderness areas alike; however, the types and quality of activities vary considerably between these two areas. Recreational opportunities are made more memorable because of the natural beauty of Yosemite Valley and wilderness environments. These areas offer a wide range of recreational experiences for the visitor, including hiking, picnicking, camping, climbing, skiing, and fishing,

Local Setting – East Yosemite Valley Utilities Improvement Plan Area

The East Yosemite Valley Utilities Improvement Plan area covers a large portion of the east Valley, from the Yosemite Creek Lift Station to the park water storage tank east of Happy Isles. Prominent natural features in the area include the Merced River, Tenaya and Yosemite Creeks, as well as Stoneman, Ahwahnee, and Cook’s Meadows. The east Valley, which is more heavily developed and visited than the western end of the Valley, encompasses Curry Village; developed campgrounds; The Ahwahnee; Yosemite Lodge; and Yosemite Village, which includes park housing, maintenance facilities, and administration offices.

Natural Resources

Soils

Most of Yosemite Valley is an active floodplain of the Merced River. During Merced River flood events, alluvial soils are formed and removed as floodwaters deposit and erode material over the floodplain. The active flooding builds river terraces of fine- to coarse-textured sands. Old riverbeds of boulders and gravel may be buried under the terrace soils. Residual soils are scattered throughout Yosemite Valley where bedrock weathering has occurred. Glacial soils are associated principally with moraines. Colluvial soils have developed on the talus slopes along the edges of the Valley floor. Valley soil textures vary from fine sand to fine gravel. Most soils have a relatively undeveloped profile, indicating their relatively recent origin and young geologic age.

Organic content within the upper soil profile varies with the local influences of moisture and drainage. Thick sedges and grasses have contributed to the organic content of soils near ponds, lakes, and streams. Coniferous forest soils have a relatively high organic content and are relatively acidic. Soils lacking organic accumulations are frequently a result of granitic weathering, consist largely of sand, and support only scattered plants tolerant to drought-like conditions.

Certain soil types have been identified in Yosemite Valley as highly valued resources.  The criteria used to designate highly valued resource soils include the potential for restoring highly valued vegetation communities, protection by federal laws, and significance as a sensitive area (such as soils that take an inordinately long time to recover from disturbance). Highly valued resource soils are found in or adjacent to meadows and riparian areas, hydric soils, and soils associated with lateral or terminal moraines. Soils in and along riparian and meadow areas are often in ecotones—areas where ecosystems overlap—and are especially rich with vegetative and wildlife diversity. Highly valued resource soils are typically more susceptible to development impacts; they lack the structure to readily support building weight and erode more easily than a resilient soil type. Therefore, a highly valued resource soil is more suitable for restoration.

Hydric soils are legally protected because they form in wetlands , which are protected by federal law. Hydric soils form under sufficiently wet conditions to develop anaerobic conditions and can usually support a predominance of hydrophytic vegetation . Hydric soils are found primarily in the river valleys of the Merced River  and Tenaya Creek and in low meadows.

Soils that are more suitable for development are identified as resilient. Resilient soils are those that are capable of withstanding alteration without permanent deformation, or recover more easily from alteration. Generally, resilient soils do not have major development limitations or restrictive physical attributes.

Other soils are not considered highly valued resources or resilient soils. Generally, these soils place more limitations on use because of steep slopes or other physical attributes. They may require more intensive management or engineered mitigation measures for development compared to resilient soils. Other soils do not fit into the highly valued resource soil resource category because they are generally more abundant and do not support plant communities that are rare or especially diverse.

Soil types in Yosemite Valley and their classification are shown in table III-1.

SOURCE:  Soil Survey of Yosemite National Park, Yosemite Valley, California (SCS 1991)

Hydrology, Floodplains, and Water Quality

Hydrology

Yosemite Valley has a number of major surface water features, including the Merced River and some of the tallest waterfalls in the world. The Yosemite Valley watershed includes Yosemite Valley and its tributary areas. The main tributaries to the Merced River in Yosemite Valley are Tenaya Creek, Illilouette Creek, Yosemite Creek, and Bridalveil Creek. The average daily discharge rate measured at Happy Isles Gauging Station at the base of the upper Merced River watershed and the beginning of the Yosemite Valley watershed is approximately 355 cubic feet per second (cfs), and the average annual total discharge is approximately 257,400 acre-feet (USGS 1998b). At the Pohono Bridge Gauging Station, just upstream of where the Yosemite Valley watershed ends and the Merced River enters the narrow, steep-sided Merced River gorge, historic flow measurements in the river have ranged from a high of about 25,000 cfs to a low of less than 10 cfs. The mean daily discharge is about 600 cfs, with an average annual total discharge of approximately 435,000 acre-feet (NPS 1978).

During the most recent period of glaciation in Yosemite Valley, a glacier extended to approximately the location of Pohono Bridge. Following glacial retreat, Lake Yosemite developed and eventually filled with sediment from the El Capitan moraine to upstream of Happy Isles (Huber 1989). The resulting Valley floor has a very mild slope and is responsible for the meandering pattern of the present-day river. The Yosemite Valley segment of the Merced River is characterized by a meandering river, world-renowned waterfalls, an active flood regime, oxbows, unique wetlands, and fluvial processes. The Merced River has a relatively mild slope, with an average of 0.1% slope through Yosemite Valley (USGS 1992). The Merced River is an alluvial river within Yosemite Valley, and the bed and banks of the channel are composed of smaller sediments, cobbles, and soil layers. This condition makes for a dynamic river that alters its course periodically by eroding and depositing bed and bank material. In most locations, the river flows through a shallow channel approximately 100 to 300 feet wide. In the middle of Yosemite Valley, the river has the capacity to convey an amount between the two- and five-year flows within the existing channel banks (NPS 1997b).

Precipitation

The overall climate is temperate, with hot, dry summers and cold, wet winters. About 85% of the precipitation falls between November and April. December, January, and February have the highest average precipitation, with a monthly average of 6 inches in Yosemite Valley at 4,000 feet. Average annual precipitation in Yosemite Valley is 36.5 inches. Snowmelt drives the peak streamflows that occur in May and June, and minimum riverflow is observed in September and October.

Alluvial Processes

Yosemite National Park is composed of and underlain by various granite rock types; as a result, weathering, erosion, and transport of sediment can be very slow processes. Areas of the park have significant soil layers where clays, silts, and organic debris have accumulated with the gravels and sands of the decomposed bedrock. These soils are subject to erosion and alluvial processes.

Sedimentation is a significant process within Yosemite Valley. As noted earlier, the Merced River has a very low gradient within the Valley, approximately 0.1%, or 6.25 feet per mile. This low gradient allows for significant sediment deposition within Yosemite Valley and the formation of the meandering Merced River through this reach. River impoundments such as bridges and dams tend to alter the sediment distribution and formative streamflows, thereby disrupting the natural alluvial processes.

Floodplains

Floodplains play a necessary role in the overall adjustment of a river system. They exert an influence on the hydrology of the basin and serve as temporary storage areas for sediment eroded from the watershed. Periodic flooding provides sediment and nutrients that are essential for the aquatic and vegetative health of the floodplain. Floodplains are features that are both the products of the river environment and important functional parts of the system. However, human-made structures such as bridges and buildings placed within a floodplain can impede natural flow and result in injury to visitors and damage to structures.

Yosemite Valley has a well-developed floodplain, with major roads and structures along or within both sides of the floodplain. The character of the floodplain varies in different locations because of local hydraulic controls. The 100-year floodplain (the area along the river corridor that would receive flood waters during a 100-year event) is typically used to define the general floodplain boundary.  A 100-year flood event is one that has a 1% chance of occurring in any given year.

The Merced River watershed has had 11 winter floods since 1916 that have caused substantial damage to property. All of these floods took place between November 1 and January 30. The January 1997 flood was the largest recorded within the park; it was estimated to have a recurrence interval of 90 years (NPS 1997b). The flood inundated roads, picnic areas, park offices, and lodging units. The U. S. Geological Survey estimated that the flood had a peak discharge of 10,000 cfs at Happy Isles and 25,000 cfs at Pohono Bridge (Eagan 1998).

A Floodplain Statement of Findings for the East Yosemite Valley Utilities Improvement Plan is provided in Appendix E.

Water Quality

Water quality throughout Yosemite National Park is considered to be good and generally above state and federal standards. The state of California considers the surface water quality of most park waters to be beneficial for wildlife habitat, freshwater habitat, contact and noncontact recreation, canoeing, and rafting, as indicated in the Central Valley Regional Water Quality Control Board’s Water Quality Control Plan (CVRWQCB 1998). An inventory of water quality data performed by the National Park Service indicated excellent conditions in many parts of the park, but some water quality degradation was noted in areas of high visitor use (NPS 1994a).

Occasional concentrations above drinking water and freshwater criteria have been noted within the Merced River for lead, cadmium, and mercury (NPS 1994a). Potential sources of these metals include leaded gasoline, stormwater runoff from developed surfaces such as parking lots, wastewater discharge, campsites, and fuel storage facilities. In particular, recent wastewater discharges into the Merced River have resulted in the previously discussed California Regional Water Quality Control Board Cleanup and Abatement Order directing Yosemite National Park to construct wastewater system improvements to prevent future unintentional discharges.

Water quality has been affected by the extensive and concentrated visitor use of the Merced River in popular areas. High use of the streambank induces bank erosion through the loss of vegetative cover and soil compaction. Bank erosion can result in the widening of the river channel and loss of riparian and meadow floodplain areas. Water quality is then altered through increased suspended sediments due to erosion, higher water temperatures from a lack of riparian cover, and lower dissolved oxygen levels due to elevated temperatures and shallower river depths.

Human activities, including the use of vehicles, can distribute water pollutants that collect on land surfaces and are later transported into the river or its tributaries by stormwater runoff. Such activities are referred to as nonpoint pollution sources because the pollutants they generate accumulate from various areas and do not originate from a single point source (such as an outfall pipe). Construction activities that disturb soil, generate dust, and cause occasional petroleum releases from equipment and vehicles can represent a short-term nonpoint pollution source. Recreational activities such as horseback riding, swimming, and hiking can lead to the introduction of organic, physical, and chemical pollutants into aquatic systems. Nonpoint-source runoff from roads and parking lots may potentially affect water quality by introducing organic chemicals and heavy metals.

Wetlands

Wetland data presented in this section are intended to provide general descriptions of wetland and water-dependent communities in the East Yosemite Valley Utilities Improvement Plan project area. Refer to the Vegetation section for descriptions of vegetation, the Wildlife section for data relating to wildlife and aquatic species, and the Special-Status Species section for information on protected species of plants and wildlife. Compliance with Executive Order 11990 on wetland protection and the National Park Service Director’s Order #77-1 on Wetland Protection is documented in Appendix F, Draft Wetland Statement of Findings for the East Yosemite Valley Utilities Improvement Plan Project.

Wetland Classification and Definition

Wetlands are transitional areas between terrestrial and aquatic ecosystems, where water is usually at or near the surface or the land is covered by shallow water. Wetlands have many distinguishing features, the most notable of which are the presence of standing water, unique soils, and vegetation adapted to or tolerant of saturated soils (Mitsch and Gosselink 1993). Wetlands are considered highly valued resources because they perform a variety of hydrologic and ecological functions vital to ecosystem integrity.

The National Park Service classifies and maps wetlands using a system created by the U.S. Fish and Wildlife Service that is referred to as the Cowardin classification system (USFWS 1979). This system classifies wetlands based on vegetative cover and life form, flooding regime, and substrate material. Jurisdictional wetlands are delineated and classified to meet regulations of Section 404 of the Clean Water Act. Cowardin wetlands include jurisdictional wetlands but may also include certain nonvegetated sites lacking soil if they meet specific criteria.

Wetlands within the Project Area

Wetlands in Yosemite Valley are formed in low-gradient land adjacent to the Merced River, its tributaries, or other bodies of water that are, at least periodically, influenced by flooding or high water tables. These wetlands would be broadly identified as riverine (Merced River), palustrine (riparian, tributaries, shallow ponds, meadows, and marshes), and undesignated (USFWS 1995). 

Specific wetland classes within the project area include the following:

• Riverine – includes all wetland and deepwater habitats contained within a river channel, except wetlands dominated by trees, shrubs, persistent emergent mosses, or lichens.

• Palustrine emergent – includes meadows, marshes, and vegetated ponds. Characterized by erect, rooted, herbaceous hydrophytes that are usually present for most of the growing season.

• Palustrine forest – riparian forest habitat that is regularly inundated by normal high-water flows or flood flows. The dominant woody vegetation is at least 20 feet tall.

• Palustrine scrub shrub – dominated by woody vegetation less than 20 feet tall, such as willows.

Vegetation

Yosemite Valley is in the lower montane mixed conifer vegetation zone, where 41 vegetation types have been identified (NPS 1994b). These have been loosely lumped into five groupings: upland, California black oak, meadow, riparian, and other.

Upland and California Black Oak Communities

Upland plant communities are found where soil moisture conditions are average to dry and where soils are not periodically flooded or saturated. In Yosemite Valley these communities fall into the categories of mixed conifer and California black oak. Due to the ecological and cultural value as well as its sensitivity, the California black oak community has been removed from the upland category and evaluated separately throughout this document.

Mixed conifer communities are much more common, widespread, and vegetatively intact than California black oak, riparian, or meadow communities in Yosemite Valley. Nearly 100 years of fire suppression has resulted in a change in the mixed conifer community from open forest to dense thickets of shade-tolerant tree species (including incense-cedar, white fir, and Douglas-fir) in many areas. Non-native plant species have become established in the mixed conifer zone, although not to the same extent as in meadows and California black oak stands.

California black oaks form a band of oaks around the Valley floor between the upland plant communities and the lower-lying meadow and riparian communities. California black oak stands mixed with ponderosa pine are found throughout the Valley, and additional areas of California black oak that have buildings and other development are found in the east Valley. California black oak communities are considered a highly valued natural and cultural resource in Yosemite Valley. Non-native plant species have also become established in California black oak communities. Due to past and current levels of disturbance in this community, non-native species have become more widespread than in upland forests. These non-native species include annual grasses, black locust, American elm, and extensive ground-covering stands of Himalayan blackberry.

Annosus root disease is a widespread native fungus occurring throughout northern Europe and western North America in coniferous forests. In pines the fungus first spreads through the root system, attacking and eventually killing the inner bark and sapwood. Within two to six years after initial infection, the tree can die, with the fungus remaining active as a saprophytic, wood-decaying organism within roots and the butt of the dead tree. Pines weakened by annosus root disease are often killed by bark beetles. Incense-cedars, however, are not affected by beetles and will stand green for many years until the disease finally weakens the structure enough to cause failure. Cedars are thought to act as reservoirs for annosus root disease (NPS 1998b).

In Yosemite Valley, the large size of annosus root disease centers is unusual; only a few other large population centers of this species occur on the western side of the Sierra Nevada. The Valley has dense stands of large trees on a sandy floor, a high water table, and frequent flooding. The conifer forest in Yosemite Valley may not be sustainable because of these large centers of annosus that have developed within the unnaturally dense stands of conifers in former California black oak, meadow, and riparian areas. Several centers of significant annosus infestation are present in the Valley today, including former Upper and Lower River Campgrounds, Yellow Pine Campground, Sentinel Beach Picnic Area, portions of Yosemite Lodge, and most of the Taft Toe area. Existing annosus centers in developed areas can be mitigated by landscaping with native species that are not susceptible to infection, such as California black oak, live oak, and big-leaf maple.

Meadow/Floodplain Plant Communities

The meadow/floodplain communities support a wide range of vegetation and in Yosemite Valley play a particularly critical role in the Merced River ecosystem. High spring flows create wet areas in side channels, low-lying wetlands, meadows, and cutoff channels. These areas support concentrations of organic matter, nutrients, microorganisms, and aquatic invertebrates throughout the relatively dry summer. When the flush of winter or spring flooding occurs, this stored aquatic biomass is washed into the main river channel. Nutrients flushed from the meadow/floodplain areas form the base of the aquatic food chain in the main river channel.

Lower Montane

Lower montane meadows on the Merced River floodplain are hydrologically controlled communities. The maintenance of these communities depends on sustaining river processes, including the frequency, duration, and magnitude of flooding, and frequent, low-intensity fires. The meadows in Yosemite Valley are transition zones from drier upland and California black oak communities to wetter riparian communities. The meadows themselves have water tables that vary seasonally and link the Merced River and tributaries to seasonally dry land. Meadow communities in Yosemite Valley are considered highly valued resources.

Yosemite Valley meadows are classified into three general types: (1) wet meadow, dominated by native hydrophilic vegetation; (2) grass meadow, dominated by non-native grasses (introduced in turn-of-the-century agriculture); and (3) native hydrophytic forbs (NPS 1994b). Meadow acreage in the Valley has substantially diminished since the mid-1800s, from 745 acres in 1866 (as mapped by state geologist J.D. Whitney) to less than half that today, primarily through human-caused conversion from meadow to upland communities. Contributing factors have been a change in prehistoric fire frequency maintained by American Indians and more recent manipulations of hydrologic patterns, including intentional draining of meadows to facilitate grazing and agricultural use, road and trail building with drainage diversions, and channelization of surface and subsurface water runoff.

As a result of these changes, many non-native species have become established in Valley meadows. Non-native grasses, planted intentionally at the turn of the century for agricultural purposes, remain the dominant species in the drier portions of most meadows. Bull thistle and Himalayan blackberry are other examples of non-native species that have proven their ability to invade and out-compete native vegetation. Non-native species alter the composition of Valley meadows, out-compete native species, and could reduce regional species diversity. Control and preventive measures are in place for many of these species.

Riparian Plant Communities

The riparian communities are vegetative communities adjacent to the main river channel and tributaries. These plant communities serve as the interface between the river and the surrounding meadow and upland communities. Riparian zones extend outward from the Merced River and its tributaries into the canopy of riverside vegetation. These communities provide specialized habitat and important nutrients to the meadow and river systems. Riparian communities are among the most productive, sensitive, and biologically diverse in Yosemite Valley. They also are among the most impacted resources due to their proximity to water and the effects of trampling and above- and below-ground infrastructure, including impacts from lift stations, bridges, and underground sewer lines.

Riparian zones in Yosemite Valley are characterized by broad-leaved deciduous trees such as white alder, black cottonwood, and willow species. Vegetation along moving water is regularly disturbed by the deposition and removal of soil and the force of flood waters. Vegetation in this zone readily colonizes newly formed river-edge deposits. Big-leaf maple riparian forests grow on moist, gravelly soils in protected spots at the base of cliffs and on alluvial soils bordering streams. They are dominated by big-leaf maples, white alder, white fir, and mountain dogwood (NPS 1994b).

Wildlife

Yosemite National Park, one of the largest and least-fragmented habitat blocks in the Sierra Nevada, supports a diverse and abundant variety of wildlife. Its importance in protecting the long-term survival of certain species and the overall biodiversity^[1] or wildlife in the Sierra Nevada was recognized in the reports prepared as part of the Sierra Nevada Ecosystem Project (UC Davis 1996).

For wildlife populations to be viable, resources and environmental conditions must be sufficient for foraging, nesting or denning, resting cover, and dispersal of animals. Arrangement, types, and amounts of resources must be sufficient for the needs of reproductive individuals on daily, seasonal, and yearly scales. Habitat must also be well-distributed over a broad geographic area to allow breeding individuals to interact spatially within and among populations, and a stable, relatively undisturbed riparian corridor supplies a mechanism for this kind of ecological connection. Concentrated areas of human use in Yosemite have affected wildlife and their habitats, especially in the east end of Yosemite Valley. Some of the most valuable and sensitive habitats are also located or once existed in the east Valley. Montane meadow and riparian areas are highly productive, structurally diverse habitats that support a high level of species diversity and provide important linkages between terrestrial and aquatic communities. The long history of development and human use in the Valley has resulted in fragmentation and reduction of these habitats, affecting their quality.

Wildlife Habitats of the Project Area

Several wildlife habitats are associated with the upland (mixed conifer and California black oak), meadow/floodplain, riparian, and other (urban) vegetation types found within the project area.

Upland Habitats

Montane hardwood, montane hardwood conifer, ponderosa pine, and Sierra mixed conifer wildlife habitats occur in the upland habitats. In the montane hardwood habitat type, acorns produced by the dense oaks provide an abundant food source for wildlife such as gray squirrel, acorn woodpecker, band-tailed pigeon, mule deer, and black bear. Snags and mature trees provide roosting and nesting cavities. Variability in canopy cover and understory vegetation make the montane hardwood conifer habitat suitable for a wide variety of wildlife species, such as black bear, acorn woodpecker, and band-tailed pigeon. Denser stands of montane hardwood conifer are a favored habitat of California spotted owls; mast crops produced by trees are an important source of food to wildlife in this habitat, and mature forests provide cavities for nesting birds.

Within the ponderosa pine habitat type, a mosaic of areas with trees of different ages and different canopy closure provides a wide variety of habitat layers for wildlife, such as Douglas squirrel, long-eared chipmunk, western wood pewee, red-breasted nuthatch, and Steller’s jay. Large snags and lightning-scarred trees can be important roosts for several bat species. Ponderosa pine habitat can be an important holding area for migratory mule deer, providing forage and thermal cover. Pileated woodpeckers favor the Sierra mixed conifer habitat, as do brown creepers, white-headed woodpeckers, Hammond's flycatcher, flammulated owl, and hermit thrush.

Acorns provided by California black oak in Yosemite Valley are an important source of food to a variety of wildlife. Mule deer and black bears forage extensively in this habitat in years of good acorn production. Acorn woodpeckers, as their name suggests, are highly dependent on this food source. Gray squirrels, ground squirrels, deer mice, and band-tailed pigeons also feed heavily on acorns. The large, mature California black oaks also provide cover and nesting habitat for species such as great-horned owls. Pallid bats favor mature oaks as roost sites. Many small birds such as ruby-crowned kinglets, yellow-rumped warblers, and western bluebirds glean the foliage for insects or hawk them in the understory.

Meadow Habitats

Fresh emergent and wet meadow wildlife habitat types occur in the meadow/floodplain vegetation type habitat. Fresh emergent wetland occupies just 0.43% of Yosemite Valley (NPS 2000a). The shallow waters in this habitat are important breeding areas for western toads and Pacific tree frogs and are used in spring by foraging mallards. Red-winged blackbirds nest in the taller vegetation.

While shrubs and trees are usually absent or sparse, they can be an important habitat component in the wet meadow and around its edge. Willow flycatchers depend on willow thickets for nesting habitat. Within the herbaceous plant community, habitat layers are often present on a smaller scale, with different plant species growing to different heights. Wet meadows are generally too wet for small mammals during periods of high water, but they are an important source of green vegetation in summer for herbivores such as mule deer. Birds such as mallards and red-winged blackbirds nest in wet meadows, where the water and tall vegetation can be barriers to predators. Pacific tree frogs and western toads breed in the shallow waters found in this habitat.

Riparian Habitats

In the riverine habitat type, nymphs of caddisflies, mayflies, and stoneflies live on the undersides of rocks and gravel, and they provide food for species such as rainbow trout and American dippers. Seasonal hatches of these aquatic insects provide important food sources for insectivorous birds and many bat species. Boulders and fallen trees in the water provide habitat diversity and substrates for organisms. Belted kingfishers dive for small fish, and mallards feed and raise broods in slower-flowing reaches.

Montane riparian habitats are of high value to wildlife, providing water, migration corridors, thermal cover, and diverse feeding and nesting opportunities. The linear nature of montane riparian habitat along streams is highly valuable to wildlife. Insects that feed on the trees provide abundant food for bats and insectivorous birds. Cavities in trees and snags provide nesting habitat for bird species such as swallows and woodpeckers. Leaves from deciduous trees that fall into the water are important sources of nutrients in the aquatic food chain.

More species and greater numbers of wildlife are found in riparian habitats than in any other Sierra Nevada habitat type (USFS 1977). For example, the density and diversity of bird species (breeding and migratory) tend to be much greater in riparian areas than adjacent areas (Gaines 1988). Some of these species, and most amphibians, are completely dependent on riparian and adjoining aquatic environments. The riparian vegetation along the river channel provides a continuous corridor for wildlife movement.

Other Habitats

The urban habitat type found in Yosemite Valley is composed primarily of stands of native vegetation interspersed with areas of development, such as campgrounds, parking areas, lodging, and housing areas. Vegetation can be similar in complexity to less-disturbed habitats, with California black oak, ponderosa pine, and incense-cedar as canopy species, and a shrub understory. The quality of these habitats for wildlife is limited by their small sizes and their proximity to human activity. Structures in developed areas can, however, provide nesting or roosting habitat for species such as cliff swallows and several species of bats. Urban habitats also contain non-native plant species that have been planted as ornamentals or for agriculture. Fruit-bearing species provide sources of food to wildlife in some urban habitats, such as the east end of Yosemite Valley.

Mammals

Mammals resident or transient in Yosemite Valley include deer mouse, California ground squirrel, western grey squirrel, broad-footed mole, Botta’s pocket gopher, ringtail, raccoon, coyote, bobcat, mule deer, mountain lion, and black bear. In recent years, sightings of mountain lions in Yosemite Valley have increased.

Fish

Fisheries resources within Yosemite Valley have historically been low in species diversity. Species native to the Merced River within the Valley probably only included rainbow trout (that migrated into the area from the San Joaquin River) and the Sacramento sucker. Human activity has altered native and non-native fish populations in Yosemite Valley over the years. Non-native rainbow trout and brown trout have been stocked throughout this portion of the Merced River and currently dominate the fisheries of this area. The Sacramento sucker is still common here, and an occasional brook trout is reported from the area, probably a result of transport from their more favorable habitat in higher tributaries.

The elimination of riparian vegetation by human trampling and placement of bank stabilization devices in some areas along the Merced River has reduced nutrients from fallen leaves in the aquatic ecosystem, affecting the food chain. The loss of soil from riverbanks caused by the lack of riparian vegetation has also led to the creation of broad, shallow stretches of the river that support few fish (CDFG 1990; USFWS 1992). Roads, ditches, utilities, and other structures in meadows have likely altered meadow hydrology, affecting water and nutrient flows into aquatic systems.

Reptiles and Amphibians

Yosemite has a particularly large number of native reptiles and amphibians: 14 snakes (one poisonous), seven lizards, one turtle, two toads, one tree frog, three true frogs, and five salamanders (including newt and ensatina). Most of these species have been found in Yosemite Valley.

Amphibians in Yosemite have suffered population declines similar to those seen in the rest of the Sierra Nevada (Drost and Fellers 1996). Two of the species of true frogs once found in Yosemite Valley are now apparently extinct: foothill yellow-legged frog and California red-legged frog. Possible factors in their disappearance include a reduction in perennial ponds and wetlands, and predation by bullfrogs, a non-native species found throughout Yosemite Valley.

Birds

Yosemite National Park’s wide range of elevations and habitats support diverse species; 150 species regularly occur in the park. Most of these species migrate to lower elevations or latitudes in the late summer and fall. Eighty-four bird species are known to nest in Yosemite Valley, but 54% of these species are rare or absent in winter. Human activity has been the suspected cause in reducing several bird species in Yosemite Valley. Valley meadows are a suitable habitat for great gray owls, but sightings of this species in Yosemite Valley are rare. Willow flycatchers no longer nest in the Valley, probably due to the loss of riparian and meadow habitat and nest parasitism by brown-headed cowbirds. Warbling and solitary vireos are also vulnerable to cowbird parasitism; for this reason, reduction of these vireo species in the park is also likely. Harlequin ducks are now rarely seen in Yosemite Valley, although a pair was observed in April 2000 on the Merced River in the Valley. A female was seen exhibiting incubation break behavior upstream of the Cascades Diversion Dam in 2002. A few weeks afterwards, four ducklings were observed with the female, which was the first record of Harlequin duck breeding in Yosemite Valley in 80 years (NPS 2003b).

Non-Native Species

Non-native wildlife in Yosemite Valley include several species of trout, wild turkey, brown-headed cowbird, and the bullfrog.

Brown trout and non-native strains of rainbow trout were introduced, and this has altered the aquatic ecosystem of the Merced River and its tributaries in Yosemite Valley. Such introductions of fish are suspected of being the primary factor in declines of native amphibian species in the Sierra Nevada (NPS 1994c; Drost and Fellers 1996).

The sensitive balance of aquatic ecosystems in Yosemite Valley has been disrupted by the presence of bullfrogs, which are voracious, non-native predators. It is not known when bullfrogs were introduced, but recent observations suggest that they currently occupy standing and slow-moving water throughout the Valley.

Brown-headed cowbird populations in the Sierra Nevada have increased (Verner and Ritter 1983), threatening native bird species. Cowbirds are nest parasites that lay their eggs in the nests of other birds, usually songbirds. This parasitism can have a devastating effect on the populations of some songbird species. Cowbirds have been implicated as a factor in the disappearance of willow flycatchers from Yosemite Valley. Currently, brown-headed cowbirds are common in Yosemite Valley and can be found in large numbers at the park’s stables and corrals, campgrounds, and residential areas.

Special-Status Species

Species Considered

The evaluation of the East Yosemite Valley Utilities Improvement Plan project considers 59 special-status wildlife species and 22 special-status plant species (see Appendix G, Special-Status Species Evaluation). These species were identified based on data gathered from the National Park Service, the U. S. Fish and Wildlife Service (USFWS 2003), the California Natural Diversity Database, and the California Native Plant Society. The National Park Service has determined that 41 species (out of 81 total) are not known or likely to occur in the vicinity of the project area. In addition, preferred habitat for 41 species is also not likely to occur in the vicinity of the project area. The remaining species are described below.

These species are further evaluated in Chapter IV, Environmental Consequences. The remaining special-status species are described in Appendix G, Special-Status Species Evaluation. Additional data on these species are included in the Biological Assessments for the Merced River Plan and Yosemite Valley Plan (incorporated by reference) (NPS 2000a, 2001), which are on file at Yosemite National Park.

Critical Habitat

Critical habitat has not been designated for any federally listed species that is known or has the potential to occur within the project area.

Special-Status Wildlife

Federal Wildlife Species of Concern

Wawona Riffle Beetle. This aquatic species is listed as a species of concern due to its limited distribution in the North and South Forks of the Merced River. Habitat includes rocks and mossy areas within the river channel. The Wawona riffle beetle is rare in rapid streams of California from 2,000 to 5,000 feet in elevation (Usinger 1956). The Wawona riffle beetle was previously known only from a few locations in California (Chandler 1954; Brown 1972); however, recently it was found in several widely scattered locations in northern California as well as southern Oregon and Idaho (Shephard and Barr 1991). Adults and larvae are found together, usually in cool, small to medium-sized mountain streams and rivers. They are most abundant in aquatic mosses and are rarely found in streams that exhibit seasonal variations in flow, heavy sediments, muddy or sandy bottoms, or low oxygen content (NPS 1997c).

Suitable habitat for the Wawona riffle beetle occurs in the Merced River through Yosemite Valley and El Portal and the South Fork of the Merced River in Wawona. It was described and named after specimens collected in the South Fork of the Merced River in Wawona. The California Academy of Sciences has records for seven specimens collected in the Merced River canyon between 1923 and 1932. These specimens were collected from 0.5 mile west of El Portal to 5.3 miles west of El Portal in rockslide areas (Roth 1972). Additional surveys have also found the beetle in the Merced River in the vicinity of Pohono Bridge (Arnold 2001; USGS 1999).

Surveys were conducted for the Wawona riffle beetle in the fall of 2001 and 2002. In 2001, surveys were conducted along an approximately 12-mile stretch of the Merced River from the Happy Isles Bridge to the Pohono Bridge and in 2002, a 3.5-mile stretch of the Merced River from Pohono Bridge to the Cascades Picnic Area was surveyed. During both surveys, suitable habitat was observed throughout the study area; however, no life-stage of the beetle was found. Suitable habitat included areas of aquatic mosses with a prevalence of partially submerged and submerged boulders, and where the river channel was at least partially shaded by trees growing along the shoreline. In more open, sunlit stretches of the river channel, such as at beaches and adjacent to meadows, mosses were occasionally observed on boulders where some shading was usually evident, but not in the more exposed areas. Due to the low water level at the time of the surveys, aquatic mosses that would normally be submerged were exposed. While the species was not observed during the surveys, it is anticipated that it would be observed in this area during periods of higher water levels, based on the presence of suitable habitat and previous observations of the beetle (Arnold 2001, 2002).

Mariposa Sideband Snail. The Mariposa sideband snail is a narrowly distributed land snail known from the Glacier Point, Curry Village, and Vernal Fall area of Yosemite, and the Merced River canyon west of El Portal (Pilsbry 1939). This snail lives in mossy rockslides with a cover of trees or shrubs (Roth 1972). It prefers stable rather than active rockslides and rock piles with open crevices rather than those filled with silt. Little is known about the reproduction and diet of the Mariposa sideband snail. It likely deposits its eggs in moist locations in its habitats. This species is reported as inhabiting rockslides near Vernal Fall and Curry Village (Roth 1972). The California Academy of Sciences has records for five specimens collected in the vicinity of Vernal Fall and the Mist Trail from prior to the period 1916 – 1932. Suitable habitat for the Mariposa sideband snail is found in Yosemite Valley and El Portal.

Sierra Pygmy Grasshopper. Sierra pygmy grasshoppers are often found in riparian areas, particularly in the spring and early summer. They are generally small (less than 2 inches) with vestigial wings. This species has been found in only a few areas: in the vicinity of El Portal (Rehn and Grant 1956) and in the Sugar Pine area of Madera County at an elevation of 4,300 to 5,000 feet (NPS 1997c). Little is known of the breeding habitat of this species or its diet, but it likely lays its eggs in the moist soil of its habitat. Suitable habitat is found in El Portal, Yosemite Valley, Wawona, and at the South Entrance.

Western Pond Turtle. Yosemite National Park is in a zone of intergradation (gradual merging) between the northwestern and southwestern pond turtle subspecies, where interbreeding makes them indistinguishable; therefore, these two subspecies are addressed here as a single species. The western pond turtle is found in the Sierra Nevada up to 6,000 feet in elevation. It is found in permanent ponds, rivers, streams, and irrigation ditches that typically have rocky or muddy bottoms and are overgrown with vegetation. Basking areas are required by this species and include partially submerged logs, rocks, mats of vegetation, or open mud banks. The western pond turtle depends on upland habitats in which individuals can over-winter, construct nest chambers, and lay eggs. Most nest chambers are excavated in compacted soils on south-facing slopes that have grassland or scrub vegetation. Eggs are laid between May and July (NPS 1997c). Park records show sightings of the western pond turtle in Yosemite Valley and El Portal. Suitable habitat for this species occurs in Yosemite Valley.

Northern Goshawk. Northern goshawks occur in Alaska, Canada, and the more northern mountains of the western United States. In California, goshawks breed in most mountain areas, where they generally remain through the winter. Their preferred habitat is moderately dense coniferous forests broken by meadows and other openings, between 5,000 and 9,000 feet elevation.

Populations of northern goshawks have been declining in western North America, including California, primarily due to habitat destruction and human disturbance. Recent surveys in Yosemite National Park suggest that the density of nesting goshawks in the park is high relative to areas outside the park (Maurer 2000), which probably reflects the high quality of relatively intact forest habitats in the park.

Nesting begins in March or April. Their eggs are laid in a stick nest built in mature live trees, usually in dense, north-facing stands of coniferous, mixed, and deciduous forests (Zeiner et al. 1990). In the Sierra Nevada, goshawks breed in elevations that support mixed conifer forests up to higher lodgepole pine forests. Nests are also frequently associated with meadow, riparian habitats, or other natural forest openings.

Except for localized effects from development, northern goshawk habitats in Yosemite are relatively intact and probably support near-natural numbers of this species. Goshawks are usually seen in Yosemite Valley between November and February, but such observations are rare and no breeding has been recorded in this area. The California Natural Diversity Database (CDFG 2003) contains records of this species throughout all but the eastern end of the project area.

Oak Titmouse. The oak titmouse is a common resident in a variety of habitats, but is primarily associated with oaks. It occurs in montane hardwood-conifer, montane hardwood, blue, valley, and coastal oak woodlands, and montane and valley foothill riparian habitats in California. It prefers open oak and oak/pine woodlands. It sometimes forages and breeds in riparian areas, and ventures into residential areas. The oak titmouse breeds from March into July, with peak activity in April and May. It roosts in a cavity in a tree or snag. It forages on foliage, twigs, branches, trunks, and occasionally on ground for insects and spiders, berries, acorns, and some seeds. It may join flocks of mixed species in winter (Zeiner et al. 1990).

Willow Flycatcher. The total population of willow flycatchers in California is estimated at around 200 pairs. This tenuous status is believed to be caused by destruction of the preferred habitat—willow thickets in meadow and riparian areas—from grazing and development. Other contributing factors could include nest parasitism by brown-headed cowbirds, nest disturbance by grazing stock, and degradation of neotropical wintering grounds.

Willow flycatchers have not been observed nesting in Yosemite Valley for nearly 35 years, with habitat destruction, human disturbance, and cowbird parasitism likely factors. A greater factor, however, has probably been the Sierrawide decline of the species, which has limited the ability of park habitats to sustain a viable population. Recent records of willow flycatchers in Yosemite include Wawona Meadow, Hodgdon Meadow near the Big Oak Flat Entrance Station, and Westfall Meadow near Badger Pass.

Harlequin Duck. California is the extreme southern extent of the range of this species. Harlequin ducks winter in marine waters along rocky coasts from San Luis Obispo County north and breed inland along fast-flowing, shallow rivers and streams. Both wintering and breeding populations of the harlequin duck have declined all over California, probably due to human disturbance along breeding streams and the damming of rivers. It is likely harlequin ducks still breed in California, but rarely. Nests are established near swift rivers or streams in recesses sheltered overhead by stream banks, rocks, woody debris, or low shrubs. Nests are usually within 7 feet of the water, but can be up to 90 feet away. In breeding areas, harlequin ducks feed primarily on invertebrates; in marine wintering habitat, mollusks and crustaceans are major foods.

A pair of Harlequin Ducks was observed in April 2000 on the Merced River in the Valley. A female was seen exhibiting incubation break behavior upstream of the Cascades Diversion Dam, and a few weeks later the female was seen with ducklings (NPS 2003b).  This represents the first breeding record for Harlequin ducks in Yosemite Valley in the last 80 years.

White-Headed Woodpecker. The white-headed woodpecker is a common, yearlong resident of montane coniferous forests up to lodgepole pine and red fir habitats, including tree/shrub and tree/herbaceous habitats. It occurs in the Sierra Nevada, Cascade, Klamath, Transverse, and Peninsular Ranges, and Warner Mountains. White-headed woodpeckers forage on live, mature conifers with deeply creviced and scaly bark. This species finds cover in nest and roost cavities and trees; they prefer semi-open areas with large, mature trees, providing 40-70% canopy. They nest in large snags or stumps in open conifer habitats, often near edges of roads, natural openings, or on edges of small clearings. Breeding occurs from mid-April to late August, with peak activity mid-June through mid-July. Cutting of logs at ground level reduces available nest sites in stumps (Zeiner et al. 1990).

California Spotted Owl. This species is found from the southern Cascades south through the entire Sierra Nevada and in the central Coast Ranges. Surveys through 1993 estimated approximately 1,600 spotted owl sites (pairs and singles) in the Sierra Nevada. California spotted owl habitat varies from oak and ponderosa pine forests to lower elevation red fir forests up to 7,600 feet in elevation. Prime habitat occurs between 3,000 and 7,000 feet. Breeding occurs from about mid-February to mid- or late-September, at which time the young are largely independent of their parents. Eggs are laid and incubated by the female from early April through mid-May. Nests are usually tree cavities, broken-off trees and snags, abandoned nests of other species, or mistletoe clumps. Trees used for nesting are usually very large. Nesting and roosting habitat of California spotted owls is typically dense forest, with a canopy closure of greater than 70%. The presence of black oak in the canopy also enhances habitat quality.

Surveys and inventories to determine the distribution and abundance of California spotted owls in the park were conducted from April through August of 1988 and 1989 by the California Department of Fish and Game. Surveys covered 142,700 acres of forest habitat at elevations between 3,000 and 7,000 feet. These elevations form a narrow band on the west slope of the Sierra Nevada. Owls were seen or responded to imitated spotted owl calls at 58 sites over the two seasons. U. S. Forest Service protocol was used to establish pair occupancy. Reproductive activity was observed serendipitously. Two nest trees and four sites with young were observed in 1989. Based on a 1988-1989 study, the known or occupied habitat for the spotted owl in the park totals about 142,000 acres (Gould and Norton 1993). In Yosemite Valley, National Park Service wildlife staff have confirmed spotted owl sightings near Happy Isles, Mirror Lake, the Chapel, and the base of Cathedral Rocks. No nesting owls occur within the project area, although suitable habitat is present (NPS 1999; 2003b)

Pale Big-Eared Bat.  This species is found in all habitats up to the alpine zone. It requires caves, mines, or buildings for roosting and prefers mesic habitats, where it gleans from brush or trees along habitat edges. The species has been recorded at Wildcat Creek Bridge and Mirror Lake (CDFG 2003), and there have been several sightings throughout Yosemite Valley.

Spotted Bat. This species is found in western North America, from British Columbia into Mexico. The spotted bat lives in desert scrub and open forest areas and roosts in cliff faces and rock crevices. The species forages in a wide variety of habitats, primarily for moths. There is a significant population of spotted bats in Yosemite Valley (Pierson and Rainey 1993). Auditory bat surveys were conducted in 1993 at 24 stations in Yosemite Valley in four habitats: large open meadows, wetlands, forest, and open ponderosa pine forest. Acoustic surveys detected the spotted bat in meadow and wetland habitats only (Pierson and Rainey 1993). The spotted bat forages on the north side of El Capitan Meadow, just below El Capitan, Bridalveil Meadow, Leidig Meadow, and Ahwahnee Meadow (Pierson and Rainey 1993). The species was not found in Cook’s Meadow or Stoneman Meadow. A study of potential bridge roosting sites along the Big Oak Flat Road found no evidence of spotted bats at any of the six sites within the park (Pierson et al. 2001).

It is likely that the spotted bat roosts on or near Half Dome and El Capitan (Pierson and Rainey 1993). Yosemite Valley had the highest population of spotted bats of any localities surveyed in California (Pierson and Rainey 1995).

Greater Western Mastiff Bat. The range of the greater western mastiff bat includes southern California and Arizona and extends into Mexico. This species is found in a variety of habitats to over 8,000 feet in elevation. This bat species roosts primarily in crevices in cliff faces and occasionally in trees and buildings; it is detected most often over meadows and other open areas but will also feed above forest canopy, sometimes to high altitudes. There is a significant population of greater western mastiff bats in Yosemite Valley, as determined by mist-netting surveys (Pierson and Rainey 1995; Pierson et al. 2001).

Auditory bat surveys were conducted in 1993 at 24 stations in Yosemite Valley in four habitats: large open meadows, wetlands, forest, and open ponderosa pine forest. Acoustic surveys detected this bat species in Bridalveil Meadow, El Capitan Meadow, Leidig Meadow, Cook’s Meadow, Ahwahnee Meadow, Stoneman Meadow, Wosky Pond, Mirror Lake, and wetlands near Happy Isles. It was also detected in a few upland habitats east of El Capitan Meadow and Sentinel Beach Picnic Area. Recent mist-netting surveys found the greater western mastiff bat in the Cascades Picnic Area (Pierson et al. 2001). Yosemite Valley has the highest population of the greater western mastiff bat of any locality surveyed in California (Pierson and Rainey 1995).

Small-Footed Myotis Bat. The small-footed myotis bat is a common bat of arid uplands in California. It is found on the west and east sides of the Sierra Nevada, in Great Basin habitats from Modoc to, Kern, and San Bernardino Counties, and in coastal California south to the Mexican border. It occurs in a wide variety of habitats, primarily in relatively arid, wooded, and brushy uplands near water, from sea level to at least 8,800 feet in elevation. The small-footed myotis bat is often seen foraging among trees and over water. Populations of small-footed myotis bats have apparently declined over recent decades, with likely causes including habitat destruction and fragmentation and the use of pesticides.

The small-footed myotis bat mates in the fall. Young are born from May through June, with a peak in late May. The small-footed myotis bat is known to occur in Yosemite Valley, based on historic records and a specimen at the Museum of Vertebrate Zoology in Berkeley, California. The small-footed myotis bat was not captured during 5 days of mist netting in Yosemite Valley in 1993, although it was captured in Wawona in 1994 (Pierson and Rainey 1993, 1995).

Long-Eared Myotis Bat. The long-eared myotis bat is found across of much of western North America, from British Columbia south to California and New Mexico. The species is found in a wide range, from the coast to the high Sierra Nevada, and in montane oak woodlands. The species lives in coniferous forests in mountain areas and roosts in small colonies in caves, buildings, and under tree bark. During mist-net bat surveys conducted in Yosemite Valley from 1993 to 1996 at Mirror Lake, Cook’s Meadow, El Capitan Meadow, Cathedral Beach and Cascades Picnic Areas, and at Yosemite Creek below Lower Yosemite Fall, the long-eared myotis bat was captured at two locations (the Cathedral Beach and Cascades Picnic Areas and at the Yosemite Creek site) (Pierson and Rainey 1993, Pierson et al. 2001).

Fringed Myotis Bat. The fringed myotis bat is found in much of California, along the West Coast up to British Columbia, and is scattered across several southwestern states and into Mexico. It is found to at least 6,400 feet in the Sierra Nevada in deciduous/mixed forests. This species feeds over water, in open habitats, and by gleaning from foliage; it roosts in caves, mines, buildings, and trees—especially large conifer snags. The fringed myotis bat found in 1924 in a location just outside the park boundary (Grinnell and Storer 1924). Mist-net bat surveys were conducted in Yosemite Valley in 1993 at Mirror Lake, Cook’s Meadow, El Capitan Meadow, and at Yosemite Creek below Lower Yosemite Fall ((Pierson and Rainey 1993, 1995). The fringed myotis bat was captured in Cook’s Meadow and at the Yosemite Creek site (Pierson and Rainey 1993). It was not found in mist-netting surveys in 1994 in Yosemite Valley (Pierson and Rainey 1995). Mist-net surveys conducted in 1996 did find the fringed myotis bat in El Capitan Meadow and at the Cascades Picnic Area (Pierson et al. 2001).

Long-Legged Myotis Bat. The range of this species includes most of western North America, as far north as Alaska and south to central Mexico. The species prefers forested mountainous areas and is sometimes found in desert lowlands. The species is found up to high elevations in the Sierra Nevada, in montane coniferous forest habitats. The long-legged myotis bat forages over water, close to trees and cliffs, and in openings in forests; it roosts primarily in large-diameter snags. This species forms nursery colonies numbering hundred of individuals, usually under bark or in hollow trees. The long-legged myotis bat was recently recorded in the park (Pierson et al. 2001), which was the first siting since it was found during the Grinnell and Storer survey (1924). These sightings were recorded at Cascades Creek and Yosemite Creek. In addition, there have been several sightings throughout Yosemite Valley.

Yuma Myotis Bat. This species is found across much of the western United States and into western Canada, usually below 8,000 feet in elevation. The species forages over open, still, or slow-moving water and above low vegetation in meadows. The Yuma myotis bat roosts in buildings, caves, or crevices; nursery colonies choose caves, mines, buildings, or under bridges. This species skims low over water to snatch up flying insects. Mist-net bat surveys were conducted in Yosemite Valley in 1993 at Mirror Lake, Cook’s Meadow, El Capitan Meadow, Yosemite Creek below Lower Yosemite Fall, and Cathedral Beach Picnic and Cascades Picnic Areas (Pierson and Rainey 1993 and1995, Pierson et al. 2001). The Yuma myotis bat was captured at Mirror Lake, El Capitan Meadow, the Yosemite Creek site, and both the Cathedral Beach and Cascades Picnic Areas. This species was also found in recent mist-netting surveys in Yosemite Valley and Wawona (Pierson and Rainey 1993; 1995) and in hand-net or visual surveys at bridge crossings at Cascades and Wildcat Creeks (Pierson et al. 2001). There have also been several sightings throughout Yosemite Valley.

State-Listed Special-Status Species, Species of Special Concern, and Species of Local Concern

Sharp-Shinned Hawk. Sharp-shinned hawks occur across most of North America, inhabiting woodlands and forests and hunting in forest openings and along edges. In California, they breed in a variety of forested habitats between 4,000 and 7,000 feet in elevation. They winter in all but the most barren and open habitats, and often descend to lower elevations.

Nests of the sharp-shinned hawk are typically located in dense stands of small conifers that are moist, cool, and well-shaded. They are often present in areas near water with little ground cover (Zeiner et al. 1990). Their breeding habitats include ponderosa pine, black oak, riparian deciduous, mixed conifer, and Jeffrey pine. Riparian habitats are preferred, and habitat with north-facing slopes are critical.

Observations of this species in Yosemite National Park are relatively rare; some records classified as Cooper’s hawk may have been sharp shinned hawks, due to their similar appearance. One record exists of a sharp-shinned hawk nest in Yosemite Valley in 1930. Sharp-shinned hawks are found throughout wooded habitat in the park from 4,000 to 7,000 feet in elevation. Habitat is largely intact in the park, except for localized habitat destruction from roads and development. Suitable habitat for the sharp-shinned hawk is found in Yosemite Valley.

Long-Eared Owl. Long-eared owls are found across most of the United States but are uncommon throughout their range. In the Sierra Nevada, this species is found from blue oak savannah up to ponderosa pine and black oak habitats, usually in association with riparian habitats. Long-eared owls will also use live oak thickets and other dense stands of trees for roosting and nesting (Zeiner et al. 1990). Numbers of long-eared owls in California have been declining since the 1940s. Known factors in this decline are destruction and fragmentation of riparian and live oak habitats, but other factors may also be present.

Records of long-eared owls in Yosemite are few, including one nesting record in Yosemite Valley in 1915. Their preferred nest sites are in trees with dense canopy coverage; the proximity of this habitat to meadow edges for hunting enhances its quality. Old crow, hawk, magpie, or squirrel nests are often used as nests. Breeding occurs from early March to late July. Long-eared owl habitat is largely intact in the park, except for localized habitat destruction from roads and development. Suitable habitat for the long-eared owl is found in Yosemite Valley.

Yellow Warbler. In California, yellow warblers breed over much of the state where suitable breeding habitat occurs. Yellow warblers breed primarily in riparian woodlands from coastal, valley, and desert lowlands, up to 8,000 feet in the Sierra Nevada. Other breeding habitat includes montane chaparral, ponderosa pine, and mixed conifer where substantial amounts of brush occur (Zeiner et al. 1990). Breeding occurs from mid-April to early August, with peak activity in June. Nesting territories often contain heavy brush understory for nesting and tall trees for foraging and singing (Zeiner et al. 1990). Destruction of riparian habitats and nest parasitism by brown-headed cowbirds have led to declines in lowland populations of yellow warblers.

Overall, riparian habitats within the park are relatively intact, but localized destruction of such habitat from foot traffic, primarily in the east Valley, has likely affected yellow warblers. Breeding habitats in forested areas are, likewise, relatively intact, but a long history of fire suppression in the park may have affected habitat quality in areas where an unnaturally high degree of canopy closure limits understory growth.

Great Gray Owl. The great gray owl is considered rare throughout its range. In California, the center of abundance of this species is the Sierra Nevada, specifically in the Yosemite area (Winter 1986). The Sierra Nevada population of great gray owls marks the most southerly population in the world (Winter 1985; Reid 1989). Surveys in Yosemite National Park and adjacent national forests estimate the California population of great gray owls at 100 to 200 birds (Winter 1986). Recent population declines in California may be due to habitat degradation from logging and grazing.

Great gray owls form monogamous pairs that breed from about March to August. Eggs hatch from mid-May to mid-June, and young fledge in early June to early July. In the Sierra Nevada, great gray owls nest in mature red fir, mixed conifer, or lodgepole pine forests near wet meadows or other vegetated openings (Zeiner et al. 1990). Their preferred breeding habitat is pine and fir forests near montane meadows that ranges from 2,460 to 7,380 feet in elevation (Winter 1986). In California, all reported great gray owl nests have been in the tops of large-diameter broken snags (Winter 1980). Nest snags are usually within a few hundred feet of a meadow. High snag densities may be critical for nesting habitat, since not all snags form top depressions suitable for nests. Nesting success is believed to depend on the abundance of voles (Winter 1986).

Owls in Yosemite restrict foraging to open meadows (Reid 1989). Adequate numbers of hunting perches are also important (Winter 1980). Meadows used by great gray owls are generally at least 25 acres in area and are in good ecological condition. The great gray owl migrates downslope in winter. Forested land from about 2,000 to 5,000 feet in elevation that contains openings suitable for vole and gopher populations is critical to sustain owls during the winter (Skiff 1995).

Meadows in Yosemite Valley appear to be good winter and staging habitat for great gray owls, but recent records in this location are rare. This could be due to the amount of human disturbance that occurs in this area. The fact that the range of nearly the entire California population of great gray owls is centered over Yosemite reflects the relatively intact condition of habitats in the park.

Pallid Bat. The pallid bat is found throughout California, primarily in the low to mid-elevations, although it has been found to elevations over 10,000 feet in the Sierra Nevada. This bat species is found in a variety of habitats, from desert to coniferous forest and nonconiferous woodlands. It is particularly associated with ponderosa pine, redwood, and giant sequoia habitats. It selects a variety of day roosts, including rock outcrops, mines, caves, hollow trees, buildings, and bridges. Recent research suggests a high reliance on tree roosts. The pallid bat commonly uses bridges for night roosts (Pierson et al. 2001). Between 1994 and 1998, mist-net bat surveys were conducted in Tuolumne Meadows, Cascades Picnic Area, Mirror Lake, Pate Valley, and Wawona (Pierson and Rainey 1993 and 1995, Pierson et al. 2001). It was captured in Yosemite Valley in 1993 (Pierson and Rainey 1993, 1995).

Townsend’s Big-Eared Bat. In California, the Townsend’s big-eared bat is found from low desert to mid-elevation montane habitats. The majority of records are from low to moderate elevations, although this species has been found from sea level to almost 10,000 feet in elevation. Maternity colonies have been found up to over 5,000 feet in elevation in the Sierra Nevada. The Townsend’s big-eared bat is concentrated in areas with mines (particularly in the desert regions to the east and southeast of the Sierra Nevada) or caves (in the northeast portion of California and karstic regions in the Sierra Nevada and Trinity Alps) as roosting habitat (Pierson and Fellers 1998). In 1994 mist-net bat surveys were conducted in Tuolumne Meadow, Pate Valley, and Wawona. The Townsend’s big-eared bat was captured in Wawona and (Pierson and Rainey 1993, 1995). It was also captured in Yosemite Valley in 1993 and 1996 (Pierson and Rainey 1993, Pierson et al. 2001).

Special-Status Vegetation

A total of 22 plant species that have federal, state, park or California Native Plant Society status have been evaluated for this analysis (see Appendix G). Six plants are classified as federal species of concern (or federal species of local concern), one of which is also listed by the park as rare; the remaining 12 plants are listed by the park as rare, and four plants are identified by the California Native Plant Society as rare. No federal- or state-listed (threatened or endangered) plant species are known to occur in Yosemite Valley. Twelve park rare plant species currently exist in the Valley: sugar stick, round-leaved sundew, stream orchid, fawn-lily, northern bedstraw, Sierra laurel, false pimpernel, azure penstemon, phacelia, wood saxifrage, giant sequoia, and ladies’ tresses.

Federal Plant Species of Concern

Yosemite Popcorn-Flower. The Yosemite popcorn-flower is an annual herb of lower montane coniferous forest, and meadows. It blooms June to July. Yosemite popcorn-flower is known only from Yosemite Valley. It has been found along the trail from Happy Isles to Mirror Lake, south of Sentinel Bridge, and in the Ahwahnee Meadow.

Yosemite National Park Rare Status

Sugar Stick. Sugar stick is found on dry, well-drained soils with abundant coarse woody debris and deep humus. It is found at lower elevations in closed-canopy forest stands with trees as young as 60 years and in mature and old growth forests of Douglas-fir, white fir, and other vegetation types. It blooms June to August. It is widespread but rare throughout its range. It is a perennial saprophytic plant that requires an association with a fungus and vascular plants for establishment. During the growing season, the plant is unmistakable and conspicuous, with pink and whitestriped stems up to over 3 feet in height.

This species occurs at scattered locations throughout Yosemite Valley. It has been found between the river and the moraine below Clark’s Bridge. Fire is thought to play an important role in its life cycle, and this species may be at risk because of many decades of successful fire suppression, as well as destruction and fragmentation of its habitat. Low-intensity underburns might be essential for its survival.

Round-Leaved Sundew. This species, an insectivorous perennial herb, is found throughout North America, but it is limited to sphagnum bogs and acidic wetlands, which is an unusual habitat in the Sierra Nevada in the lower to upper montane coniferous forests. It blooms July to August. Habitat for this species exists in isolated areas in Yosemite Valley.

Stream Orchid. This species, a perennial herb in the orchid family, is widely distributed throughout California and North America. In Yosemite, it is restricted to moist granitic ledges and planted in landscaped areas. It blooms May to July. This species occurs in Yosemite Valley within a number of landscaped areas. Former populations above Happy Isles were obliterated by the rockfall in 1996. Natural habitat for this species exists throughout the Valley in perennially moist, shaded areas.

Northern Bedstraw. This species, a perennial herb in the bedstraw family, is found in moist areas within montane coniferous forests. It blooms June to August. It has a disjunct population in Mariposa County, within Yosemite Valley meadows. The remainder of its range is in northern California and the Pacific Northwest. In the park, this species is known from a number of wet meadows in Yosemite Valley, and wet portions of drier meadows and oxbows. It has been found in the Ahwahnee Meadow.

Sierra Laurel. This shrub, a perennial in the heath family, is found slightly beyond California’s boundaries and is restricted to wetland, bog, and moist habitats. It blooms June to August. In Yosemite, sierra laurel grows adjacent to iron-rich springs and seeps in isolated locations along the Merced River and Tenaya Creek in Yosemite Valley.

False Pimpernel. This annual herb in the snapdragon family is found in freshwater wetlands and meadows at low to mid elevations in California and North America. It blooms July to September. False pimpernel is found in meadow soils throughout Yosemite Valley that remain moist for the duration of the plant’s seasonal life span.

Azure Penstemon. This perennial herb in the snapdragon family is endemic to California and is near its southern extent in Yosemite. It is generally found in moist woodlands and open forests at lower to moderate elevations in the Sierra Nevada. It blooms May to August. This herb is found in scattered locations in Yosemite Valley. It was first described from collections taken in the Valley, although that original population appears to have disappeared.

Phacelia. This annual herb in the waterleaf family is found throughout California and is confined to western North America. It grows in seasonally moist, sandy and gravelly open areas. It blooms March to May. This species occurs at scattered locations throughout Yosemite Valley, where it blooms and sets seed early each spring.

Wood Saxifrage. This perennial herb in the saxifrage family is endemic to California and limited to the northern and central Sierra Nevada. It reaches its southern extent in Mariposa County, where it grows on mossy rocks and moist cliffs in lower to montane coniferous forests. It blooms June to July. This species occurs at scattered locations in moist, shaded sites throughout Yosemite Valley.

Giant Sequoia. Giant sequoias are endemic to California and grow in 70 discrete groves in the central and southern Sierra Nevada within the montane forest belt. In Yosemite National Park, sequoias grow naturally in the Merced, Tuolumne, and Mariposa Groves. Individual sequoia trees have been planted in Yosemite Valley and Wawona in landscaped and natural areas, both historically and in recent times.

Ladies’ Tresses. Ladies’ tresses occur in the Pacific Northwest, California, and Utah. This species is found in meadows and along riverbanks at low to middle elevations. It blooms July to August. This species, which occurs at scattered locations throughout Yosemite Valley, is a perennial orchid to 24 inches in height.

California Native Plant Society Rare Status

Yosemite Tarplant. Yosemite tarplant occurs in mixed conifer and montane zones within damp to wet, open, grassy areas and seeps. It blooms May to July. This species occurs in small, widely-scattered populations throughout most of the park below the subalpine.

Nuttall’s Pondweed. Nuttall’s pondweed occurs in the mixed conifer zone within shallow ponds, lake margins, and slow-moving streams. It blooms July to October. In Yosemite, Nuttall’s pondweed is known only from Yosemite Valley.

Air Quality

Yosemite National Park is classified as a mandatory Class I area under the Clean Air Act (42 USC 7401 et seq.). This air quality classification is aimed at protecting national parks and wilderness areas from air quality degradation. The Clean Air Act gives federal land managers the responsibility for protecting air quality and related values, including visibility, plants, animals, soils, water quality, cultural resources, and public health from adverse air pollution impacts. The U.S. Environmental Protection Agency has set national standards for six pollutants: ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, and particulate matter less than 10 microns (PM₁₀)_. In addition, California has set ambient air quality standards that are stricter than the national standards.

Yosemite Valley is in Mariposa County, which is regulated by the Mariposa County Air Pollution Control District. The Mariposa County Air Pollution Control District is responsible for developing a state implementation plan for federal and state nonattainment pollutants. State implementation plans define control measures designed to bring areas into attainment with federal and state air quality standards. Currently, Mariposa County is in attainment or is unclassified for all national ambient air quality standards; however, Mariposa County exceeds two California ambient standards: ozone (throughout the county) and PM₁₀ (in Yosemite Valley).

Sensitive Receptors

Schools, child care centers, hospitals, and convalescent homes are considered to be more sensitive than the general public to poor air quality because the population groups associated with these land uses have an increased susceptibility to respiratory distress. Persons engaged in strenuous work or exercise also have increased sensitivity to poor air quality. Residential areas are considered more sensitive to air quality conditions than commercial and industrial areas because people generally spend longer periods of time at their residences. Recreational areas are also considered sensitive compared to commercial and industrial areas due to the greater exposure to ambient air associated with outdoor activities. Trail and recreational users in Yosemite Valley would be the closest sensitive receptors to activities associated with this project.

Noise

By definition, noise is human-caused sound and is considered to be unpleasant and unwanted. Whether a noise is considered unpleasant depends on the individual listening to the sound and what the individual is doing when the sound is heard (e.g., working, playing, resting, or sleeping). Natural sounds within Yosemite Valley are not considered to be noise. These sounds result from natural sources such as waterfalls, flowing water, wildlife, wind, and rustling tree leaves. The existing noise from within the park results from mechanical sources such as motor vehicles, generators and aircraft, and from human activities, such as talking and yelling.

Sound and noise levels are measured in units known as decibels (dB). For the purpose of this analysis, sound and noise levels are expressed in decibels on the “A” weighted scale (dBA). This scale most closely approximates the response characteristics of the human ear to low-level sound. Human hearing ranges from the threshold of hearing (0 dBA) to the threshold of pain (140 dBA). Environmental sound or noise levels typically fluctuate over time, and different types of noise descriptors are used to account for this variability. One of these descriptors is the day night noise level average, which reflects the noise level averaged over a 24-hour period.

Current sound levels in Yosemite Valley vary by location and also by season (the volume of water in the waterfalls and rivers is lower in the fall and higher in the spring). Noise levels are also influenced by the number of visitors to the park and by the proximity of mechanical noise sources. Winter ambient noise levels at various locations in Yosemite Valley were measured in 1999 (NPS 2000a). Ambient noise levels ranged from 59 to 69 day-night level. Summer ambient noise levels would be expected to be higher due to the level of visitation and activity during summer months.

Existing Noise Sources

Motor Vehicles

Within the park, motor vehicle noise is more noticeable in Yosemite Valley, where there is a concentration of park visitors, vehicle traffic is heavy, and the topography places visitors in proximity to roads. But the existing noise environment changes dramatically throughout the year directly in proportion to the level of use (i.e., the number of cars and buses that travel the various roadways in the park); therefore, noise levels are generally lower during the winter than during the busy summer months.

Noise from motor vehicles is loudest immediately adjacent to the roadways, but due to generally low background sound levels, can be audible a long distance from the roads. Atmospheric effects such as wind, temperature, humidity, topography, rain, fog, and snow can affect the presence or absence of motor vehicle noise. Logically, noise levels from motor vehicles will be loudest where and when activity levels are the greatest and nearest to the sources of noise.

Aircraft Noise

As part of a report to Congress (NPS 1994d), the National Park Service conducted a visitor survey in Yosemite National Park. Of the visitors surveyed, 55% reported hearing aircraft sometime during their visit. The report notes that recognition of noise from aircraft was highly variable from location to location, and impacts to visitors were greater in areas with less vehicle noise and fewer people. In Yosemite, a majority of the comments came from wilderness trail users.

Other Sources

Other mechanical sources of noise within Yosemite Valley include construction equipment, generators, radios, and park maintenance equipment. Noise from these sources varies by season.

Cultural Resources

Overview of Human Occupation

American Indians

The area now comprising Yosemite National Park has been inhabited by people for at least 6,000 years. The park area contains hundreds of archeological sites, evincing thousands of years of occupation. There is evidence of technological change through time, a highly developed trade network, at least one population replacement, and significant environmental manipulation through the use of fire.

When Euro-Americans first entered Yosemite Valley in 1851, the Indians living there were most likely a mixture of Southern Sierra Miwuk, Mono Lake Paiute, and Central Sierra Me-wuk. The upland areas of the Merced River drainage were frequented by Southern Sierra Miwuk, possibly Mono Lake Paiute, and at least traversed by Western Monos and possibly Chukchansi Yokuts.

As awareness of Yosemite Valley grew, hotels and other travel-related amenities were developed. Management of the Valley was taken over by Euro-American institutions, and American Indian interests were subject to decisions made without their influence. Customs changed as Indian people built nontraditional houses, vacated old village sites, and built new villages. These changes were due in part to efforts as late as the 1920s by the National Park Service to centralize the Indian people as a tourist attraction and control their activities.

At least seven Indian tribes claim traditional associations with Yosemite National Park, and the National Park Service has entered into various agreements with the American Indian Council of Mariposa County, Inc., the political organization representing the Southern Sierra Miwuk tribe. The Southern Sierra Miwuk tribe is the group that has the closest cultural association with Yosemite Valley, El Portal, and into the Wawona area.  Individuals from most of these tribes continue to maintain cultural associations with lands and resources in Yosemite National Park through traditional ceremonies, gathering of traditional plants, and other activities.

Euro-Americans

During the mid-1850s and 1860s, painted, photographic, and literary images of Yosemite's beauty drew people to the area. The first tourist excursion to Yosemite Valley was organized by James M. Hutchings in 1855. By 1860, entrepreneurs had constructed hotels to capitalize on what would become a thriving tourist trade. Homestead claims were filed, orchards were planted, and Yosemite Valley became a residential base for many families.  In 1864, Yosemite Valley and the Mariposa Grove of Big Trees was granted to the State of California.  

By 1870, the establishment of visitor hotels in Yosemite Valley had created a need for local fresh produce and livestock. James Lamon, Yosemite Valley's first Euro-American homesteader, became one of the largest producers of commercial agricultural products in Yosemite Valley. Remnants of two of his orchards still exist, as well as another orchard. With the introduction of crops and livestock came fences, outbuildings, and other developments that detracted from the beauty of Yosemite Valley. The single event with the biggest permanent impact on the natural landscape of Yosemite Valley was the blasting of a portion of the glacial moraine at the foot of El Capitan in 1879.

Due to the early conservation movement led by people such as John Muir and Robert Underwood Johnson, Congress passed an act establishing Yosemite National Park in 1890. One of the birthplaces of the nationwide conservation movement was in Yosemite National Park. In 1907, acting superintendent Major H. C. Benson identified the need to develop a general plan to beautify the Valley and make all bridges, buildings, and roads conform to a plan suited to the landscape. The U.S. Army Corps of Engineers built many bridges and roads between 1905 and 1915 (Carr 1998).

By 1930, Yosemite's managers outlined areas of particular concern, including activities that encroached on meadows. The committee recommended that a landscape map be prepared to record the areas occupied by forests, woodlands, chaparral, and meadows. They also wanted to document the historic distribution of natural landscape types from photographs and records.

Starting in the 1930s, the Civilian Conservation Corps also completed an extensive range of projects in Yosemite, including construction of roads, trails, bridges, fire roads, fire buildings, fire lanes, fire trails, comfort stations, and campgrounds. Additional projects included river and creek bank stabilization, revegetation, extensive landscaping, and debris cleanup. Between 1950 and 1966, a second major building program, called Mission 66, resulted in seven new structures in Yosemite Village. Only one was built in the rustic style; the others were built in the new Mission 66 style.

Archeological Resources

Past and ongoing studies have indicated that Yosemite National Park is rich in archeological resources. Yosemite Valley has been designated as an archeological district, with more than 100 sites containing evidence of human occupation and land use over several millennia. Archeological sites with high data potential are considered highly valued cultural resources.

To date, approximately 6% of park lands have been inventoried for archeological resources, and over 1,100 archeological sites have been documented. Most of the inventories focus on lower elevation developed areas and road corridors.

The Yosemite Valley archeological district is listed in the National Register of Historic Places. Early archeological surveys of Yosemite Valley focused on prehistoric or historic Indian sites rather than historic-era resources representative of homesteading, visitor, and National Park Service facilities. The entire Yosemite Valley has been surveyed for prehistoric resources, except for wet meadows, areas of impenetrable vegetation, and some talus slopes. Some historic-era archeological deposits have been documented, and areas of known historic development are documented on historic base maps.

The archeological district comprises over 100 known sites, many of which are significant for their ability to yield important information about prehistoric lifeways. The prehistoric sites contain milling stations (granite boulders with mortar cups or milling slicks, the most common feature documented to date); midden soils; artifact scatters (including obsidian waste flakes, obsidian and ground stone tools), soapstone vessel fragments, and dietary faunal remains; rockshelters; pictograph panels; human burials; artifact caches; house floors; fire hearths; and rock alignments. Historic archeological sites contain trash deposits, building foundations, privy pits, utilities, human burials, and landscape features such as ditches, roads, rock alignments, non-native plants, and trails. . Many of the archeological sites are known only from surface evidence; most have not received subsurface excavation to better understand their contents, extent and the integrity of deposits. 

Individual sites in the archeological district vary by type, size, depth, complexity, length of occupation, variety of remains, and potential to yield important scientific information. A recent synthesis and parkwide archeological research design (Hull and Moratto 1999) provides guidance in assessing the research potential of these sites. Important questions are identified in the areas of paleoenvironment, cultural chronology, economic patterns, settlement patterns, demography, and social organization. Sites are considered significant when they contain important information that relates to these areas of inquiry.

While the majority of archeological sites in Yosemite Valley retain a relatively high degree of integrity, many have been disturbed by human activity and natural processes (Hull and Kelly 1995). Visitor use has the most widespread impact, although its effect is not as serious as other types of impacts. Due to the scarcity of easily buildable land, several archeological sites have been damaged by construction of facilities and utilities. Many roads, hotels, and other visitor accommodations have been constructed since 1957, and appreciation and preservation of cultural resources is a relatively recent development.

Traditional Cultural Resources

Traditional cultural resources are any “ . . . site, structure, object, landscape, or natural resource feature assigned traditional, legendary, religious, subsistence, or other significance in the cultural system of a group traditionally associated with it" (NPS 1991). A traditional cultural property is a traditional cultural resource that is eligible for inclusion in the National Register of Historic Places.

Proposed actions could affect properties that are associated with cultural practices or beliefs of culturally associated American Indian people (traditional cultural properties). These include plant-gathering areas, spiritual places, places that figure in oral traditions, and historic village locations. The protection of ancestral burial areas is also an important concern of Indian people. Known human burials in Yosemite Valley are considered highly valued cultural resources and are protected by avoiding these remains (NPS 2000a).

Indian people continue their traditional cultural associations with park lands and resources. While little formal research has been conducted to inventory and document traditional resources important to Indian people, Yosemite Valley has been the focus of such a study.

A recent traditional cultural study of Yosemite Valley identified and documented some of the cultural and natural resources associated with some of the American Indian occupation and use of Yosemite Valley (Bibby 1994). American Indians still living in the region provided oral history and assisted in the location of resources. The area evaluated extended from Pohono Bridge east to Mirror Lake and Happy Isles and included historic areas of human habitation, sites of traditional and contemporary spiritual value, marked and unmarked graves, and areas of past and present resource gathering and food processing. Resources included bedrock mortars and plant materials, such as California black oak groves and individual trees, grasses, mosses, sedges, and mushrooms. Most sites and features are historic, and tradition indicates that many have long histories of use. The traditional cultural evaluation recommended that Yosemite Valley be designated a traditional cultural property and listed as such in the National Register of Historic Places.

In addition, the National Park Service has initiated consultation, which will be ongoing for the duration of this project, with American Indian groups claiming affiliation with land and resources in Yosemite Valley. These are primarily the Southern Sierra Miwuk (American Indian Council of Mariposa County, Inc.) and the Mono Lake Paiute (Mono Lake Indian Community). Chukchansi Yokuts,  Western Mono groups and many Central Sierra Me-wuk individuals may have some family ties to Yosemite Valley.

Cultural Landscape Resources, Including Historic Sites and Structures

Cultural landscapes are the result of the long interaction between people and the land, and the influence of human beliefs and actions over time upon the natural landscape. Shaped through time by pre-historic and historical land use and management practices, as well as politics and property laws, technology, and economic conditions, cultural landscapes provide a living record of an area’s past, a visual chronicle of its history. The dynamic nature of modern human life contributes to the continual reshaping of cultural landscapes, making them a good source of information about specific times and places, but at the same time rendering their long-term preservation a challenge.

The cultural processes of defining sacred space, of turning land into landscape, and of making a wild place into a public park have made Yosemite Valley one of the most culturally significant natural places in America. Thus, the significance of the Yosemite Valley cultural landscape cannot be described or assessed apart from its significance as a natural landscape. Landscapes depend on unity for their emotional effect, and at Yosemite this unity combines the pastoral and the awesome, the natural and the cultural, the past and the present. The Valley's cultural landscape encompasses cliff walls, meadows, the river and streams, as well as roads, trails, and buildings.

A determination of eligibility for the National Register of Historic Places has been prepared for the Yosemite Valley Cultural Landscape. This determination of eligibility recognizes the national level of historical significance of Yosemite Valley as a cultural landscape, from American Indian occupation and resource management of the area prior to European discovery to 1945. The boundaries for the historic district extend from Pohono Bridge to Mirror Lake and Happy Isles and encompass a number of historic trails. The determination of eligibility provides an in-depth analysis of Yosemite Valley as a single entity, describes the Valley's cultural significance and characteristics, and lists both prehistoric and historic resources that contribute to the landscape's significance.

Many historic sites and structures within Yosemite Valley have been singled out for their significance and are either National Historic Landmarks or listed in the National Register of Historic Places. Historical resources in Yosemite National Park were identified and evaluated in 1979 in the Cultural Resources Management Plan (NPS 1979) and in the memorandum of agreement (1979) among the California State Historic Preservation Officer, the National Park Service, and the Advisory Council on Historic Preservation, and its accompanying correspondence. A subsequent Historic Resources Study (NPS 1987) and other project-specific reports identified and evaluated structures and sites not addressed in those earlier documents.

The Yosemite Village Historic District consists of several structures and facilities representing the residential and administrative core of Yosemite Valley. All phases of National Park Service architecture are present in the Yosemite Village, from structures designed and built by the U.S. Army to fine examples of Rustic architecture, as well as examples of Mission 66 architecture. The Ranger Club, a National Historic Landmark and an early (1921) example of the Arts and Crafts-inspired Rustic style in the park, set the tone for future building in the area.

The Ahwahnee, which is also a National Historic Landmark, was built in 1927 to provide first-class service and attract wealthy and influential visitors to Yosemite Valley. The hotel was designed by Gilbert Stanley Underwood to harmonize with the nearby rugged Valley walls. LeConte Memorial Lodge is also a National Historic Landmark structure and one of the focal points for the Sierra Club in Yosemite Valley. It was constructed by the Sierra Club in 1903 in honor of Joseph LeConte, one of its founding members. In 1919, it was moved from its original location, adjacent to Camp Curry, to its present location south of the river between Curry Village and Sentinel Bridge.

The Camp Curry National Register Historic District includes Mother Curry's bungalow and the Foster Curry cabin; the original registration building; several bungalow units; and canvas tent cabins. The camp itself dates from 1899, with changes and additions through the early 1920s. The tent cabins constitute the most significant and intact tent cabin complex left in the National Park System. Other structures, not associated with the development of original Camp Curry, still retain historical integrity and are considered contributing elements in the developed landscape.

Camp 4 (Sunnyside Campground) was recently determined eligible for listing in the National Register of Historic Places for its association with the growth and development of rock climbing as a recreational/entertainment activity in Yosemite Valley. While camping is important as a recreational activity and land use in the historical context of the Yosemite Valley cultural landscape, the individual campgrounds themselves do not retain historical integrity and therefore are not considered contributing resources. However, Camp 4 is significant as a historic site for other reasons. From 1947 through 1970, Camp 4 was a meeting ground and important focal point for climbers in Yosemite Valley, and it served as a place of training, ascent planning, information and equipment exchange, and camaraderie.

In addition, eight granite-faced, concrete-arched, two-lane vehicle bridges were constructed along the Valley Loop Road between 1922 and 1933. Six of the bridges (Ahwahnee Bridge, Clark’s Bridge, Pohono Bridge, Sugar Pine Bridge, Happy Isles Bridge, and Stoneman Bridge) cross the Merced River, while two others, Yosemite Creek Bridge and Tenaya Creek Bridge, cross these creeks. Each bridge is listed on the National Register of Historic Places.

Social Resources

Scenic Resources

Yosemite National Park’s scenic resources are a major component of the visitor’s experience, and conserving the scenery is a crucial component of the National Park Service 1916 Organic Act and the park’s enabling legislation. The park was established primarily for its natural and scenic features. The Merced River, El Capitan, Half Dome, and the Valley’s magnificent waterfalls are some of the resources that contribute to the highly valued visual quality of the park.

The 1980 General Management Plan identifies 11 significant scenic features, all of which are visible from Yosemite Valley: Half Dome, Yosemite Falls, El Capitan, Bridalveil Fall, Three Brothers, Cathedral Rocks and Spires, Sentinel Rock, Glacier Point, North Dome, Washington Column, and Royal Arches. The General Management Plan also documented a scenic analysis of Yosemite Valley that evaluated all points from which these 11 features were typically viewed (assuming that no vegetation or structures obstructed the view) and the scenic viewing possibilities from different locations on the Valley floor. Existing viewpoints were identified, and the quality of views and proximity to roads and trails were noted. Views from the various locations in the Valley were classified according to the criteria shown in table III-2. The results of the scenic analysis are graphically documented in the Yosemite Valley Scenic Analysis presented in the Yosemite Valley Plan (incorporated by reference) (NPS 2000a).

Recreation

Most visitor activities in Yosemite Valley take place in the developed eastern end and along trails leading from these areas to features above the Valley floor. The east Valley is the location of all Yosemite Valley visitor accommodations, campgrounds, and major facilities and services provided by the National Park Service and concessioners. Many visitors drive along the Southside Drive/Northside Drive loop to tour the features of the west Valley, and some visitors bicycle or walk to west Valley destinations.

Visitors enjoy numerous recreational activities while in Yosemite Valley. Many recreational opportunities are directly dependent on the attributes of the Valley; others can be experienced in many other places. In a 1990-1991 visitor study, respondents were asked to identify the activities that any party member had participated in while in the park. About 90% of visitor groups reported sightseeing as a popular activity. About 35 miles of hiking trails are available on the Yosemite Valley floor; approximately 22 miles are shared with horseback riders and 12 miles are shared with bicyclists. There are several walking loops in the east Valley. Bicycling is a common means for enjoying and exploring Yosemite Valley. More than 12 miles of multi-use paved trails have been constructed in Yosemite Valley. Climbing in the Valley includes wilderness/adventure climbing, traditional climbing, big wall climbing, recreational climbing, sport climbing, speed climbing, bouldering, big drop rappelling, and free solo climbing.

Horse use in Yosemite Valley includes private stock users and concessioner trail rides. About 14,000 visitors take concessioner-guided trail rides originating at the Yosemite Valley stable each year. The great majority of these are 2-hour trips in the east Valley. Picnicking is also popular in Yosemite Valley. Winter activities include, but are not limited to, cross-country skiing and snowshoeing. Swimming in the Merced River, Tenaya Creek, and Mirror Lake is popular among summer visitors in Yosemite Valley. Fishing requires a state license, available in shops in the Valley, and is popular during the state's season from April through mid-November. Many visitors go on 2-hour Valley floor tours, which are available throughout the day for visitors seeking an informative and scenic experience in Yosemite Valley. The ability to sit or stand quietly is basic to the park experience. Artistic pursuits are also fundamental to the enjoyment of Yosemite Valley. Bird and animal observation and nature study are also popular.

Park Operations and Facilities

Transportation

Yosemite Valley‘s transportation facilities include main roads, spur roads, access drives, pedestrian trails, multi-use paved trails, and parking areas.

Roadways and Traffic

There are approximately 30 miles of roadway traversing the Valley floor. These roadways are maintained year-round. The Valley Loop Road (comprised of Southside and Northside Drive) is an approximately 12-mile long combination one-way/two-way loop road that provides primary circulation within Yosemite Valley. It also connects with other major roads, facilitating through-park traffic. The pavement width is about 21 feet and there are two travel lanes. Four bridges across the Merced River connect the roadway running parallel to the south Valley wall (Southside Drive) with the roadway on the north (Northside Drive). One-way operation is maintained along Southside Drive from Pohono Bridge at the west end of the Valley to Stoneman Bridge near Curry Village. Two segments of one-way operation are maintained on Northside Drive: one from Stoneman Bridge to Yosemite Village, the other from Yosemite Lodge to Pohono Bridge. Two-way traffic is allowed between Yosemite Lodge and Yosemite Village on Northside Drive. In addition to Pohono and Stoneman Bridges, connections between Northside and Southside Drives are provided at El Capitan Bridge near El Capitan, and at Sentinel Bridge near the Yosemite Chapel.

Excess vehicle circulation is common, as visitors seek the best routes to their destinations and search for limited parking spaces. The turnouts along the road in the Sentinel Meadow area are heavily used. From this point east, visitors enter the developed portion of the Valley, and in peak season are exposed to generally crowded conditions and pockets of high levels of development and activity. High traffic volumes within Yosemite Valley, along with inadequate parking and visitor confusion, can create congestion during the peak season. Highly congested locations include the intersections at Yosemite Village and at the entrance to the Lower Yosemite Fall area along Northside Drive. Other congestion points include the four-way intersection near Curry Village and the intersection of Village Drive with Ahwahnee Road at the north end of Yosemite Village.

Parking

Visitor parking areas are dispersed at all the primary developed areas in the Valley and include a combination of day and overnight parking areas, roadside pullouts, shared-use areas, and employee parking. Competition for limited parking is intense during the peak season.

Parking for day-visitor vehicles is available in the Valley, primarily at the Village Store parking area, Camp 6, at various destination areas, and along Northside Drive and Southside Drive. Dedicated day-visitor parking is provided at Camp 6. The parking area was newly configured in 1999 to expand the available parking and make parking more efficient. Of the 1,662 day-visitor spaces available, an estimated 904 spaces are provided for day visitors in the most heavily visited east Valley. Most day-visitor parking spaces are also used by overnight visitors touring the Valley, as well as by residents and commuting employees. Many of the spaces are in informal pullouts and other areas that are best suited to short-term use associated with auto touring. Parking for overnight guest vehicles is available at lodging and campground areas.

Bridges

There are numerous bridges in the east Valley, including both pedestrian and vehicle bridges over the Merced River and some of its tributaries. Seven bridges in the project area are listed on the National Register of Historic Places: Yosemite Creek Bridge, Stoneman Bridge, Ahwahnee Bridge, Sugar Pine Bridge, Clark’s Bridge, Tenaya Creek Bridge, and Happy Isles Bridge.

Utilities

As described in Chapter II, there is an extensive system of water, wastewater, electric, and communications utility systems in Yosemite Valley. These utilities are generally operating within the capacity for which they were designed, with a few exceptions. The wastewater collection system in Yosemite Valley has experienced problems with leakage and resulting infiltration into the ground. Due to these problems and recent releases, the California Regional Water Quality Control Board has issued a Cleanup and Abatement Order to the park requiring substantial improvements to the wastewater collection system in the Valley. The National Park Service has developed an extensive wastewater capital improvement program to address the wastewater. (This environmental assessment evaluates the park’s proposed improvements as presented in Alternatives 1, 2, and 3.)

The wastewater collection system in Yosemite Valley contains over 11 miles of force main as well as many miles of gravity pipe varying in size from 3 inches to 18 inches in diameter (Kennedy/Jenks 2003). The wastewater collection system contains three major lift stations: North Pines, Lower River, and Yosemite Creek. Wastewater from the east Valley is pumped to the Yosemite Creek Lift Station. From there, wastewater is pumped to the wastewater treatment plant in El Portal, which has a capacity of 1 million gallons per day.

The Yosemite Valley water system is supplied by three wells located east of Yosemite Lodge along the Merced River. The system has the capacity to produce about 3.8 million gallons per day. The water supply wells generally pump water into a 2.5-million gallon tank at the southeast end of the Valley, south of the Happy Isles area (figure II-2). The water storage tank is the highest point in the water system, and the elevation provides head to pressurize the distribution system (Kennedy/Jenks 2003). The water storage tank is filled at night when water demands are low via a single line, which also feeds the water system for all Valley facilities. Under normal operating conditions, the well pumps are not used during the day and water is supplied to Valley facilities from the storage tanks.

The National Park Service purchases power from the Pacific Gas and Electric Company, which it distributes and resells to end users in Yosemite Valley, predominantly to the concessioner. Electricity is carried into Yosemite Valley by a 70,000-volt transmission line that runs overhead through El Portal and the Merced River gorge to the substation at the old Cascades powerhouse. The powerhouse is no longer active as a hydroelectric generator but is still used as a substation. From the powerhouse, the power is stepped down to 12,000 volts. Conductors in 6-inch conduits run beneath El Portal Road to a substation in Yosemite Village. The primary electric distribution system is generally in good condition after upgrades over the last 12 years, although some areas in Yosemite Valley still require rehabilitation.

SBC (formerly Pacific Bell) supplies telephone service to Yosemite Valley. The Valley’s primary communications system consists mostly of direct buried communications cables and microwave facilities. Because the communications cables were installed by the supplier, the cable locations are not all known (Kennedy/Jenks 2003). Recent technology changes, including the increasing use of remote monitoring technology for utility systems and other data intensive operations, have highlighted a need for improved data transmission capabilities, particularly between the Valley and the El Portal Administrative Site.

Park Operations

The superintendent is responsible for overall management and operation of the park. Yosemite is operationally organized into seven divisions, each with a functional area of responsibility. Park operations and facility staff, particularly the Division of Maintenance and Engineering and Division of Resources Management, would be responsible for overseeing contract work undertaken for the project. Maintenance and Engineering responsibilities include buildings and grounds, roads and trails, utilities, and design and engineering. Resource Management responsibilities include natural and cultural resource monitoring and evaluation, impact mitigation, and wildlife management. In the Maintenance and Engineering Division, approximately 64 National Park Service personnel are currently assigned to Utilities, with annual salary and operations costs of approximately $5.8 million.

Socioeconomics

The affected socioeconomic region includes Madera County, Mariposa County, and Tuolumne County, the three counties in which Yosemite National Park is located. The Yosemite Valley Plan provides a socioeconomic profile of the regional economy for 1996 that presents the size of each county’s principal economic sectors in terms of population, employment, and output. Output data have been updated based on trends in local area personal income provided by the U.S. Bureau of Economic Analysis through the year 2000 (the most recent data available for the area). The resulting estimates for 2000 provide a reasonable socioeconomic profile of the three-county region, given that it has not experienced any significant structural changes to its economy since 1996. Employment data for 2000 is provided by the California Employment Development Department.

Regional Economy

Population

In 2000, the total population of the three-county affected region was approximately 194,740 (see table III-3). Madera County is the most populous county, with roughly 123,109 residents. Mariposa County has a total population of approximately 17,130 residents.

SOURCE: U.S. Bureau of the Census 2002

Employment

The employment figures include all waged, salaried, and self-employed jobs in each county, and both full-time and part-time workers. In 2000, total employment was approximately 60,040 in the three-county area. Approximately 65% of the total employment in the affected region was in Madera County. Mariposa County accounted for approximately 8% of total employment in the affected region. Table III-4 provides total employment estimates for the counties by industry sector.

^a   Totals may not exactly compute due to rounding.

SOURCE: California Employment Development Department 2002

Output

Economic output is a measure of productivity. Measures of economic output vary depending upon the industry sector. For the agricultural, wholesale trade, and retail trade sectors, output is measured by the value of products sold. In the manufacturing sector, output is a measure of the value added by the manufacturer or the value of shipments. In the service sector, output is measured as receipts in dollars.

The estimated total output of goods and services for the three-county affected region in 2000 was about $6.9 billion (2000 dollars) (table III-5). Madera County accounted for approximately 66% of total economic output in the affected region. Mariposa County, which had the smallest economy in the affected region, accounted for approximately 7% of output. Based on output, manufacturing was the largest economic sector in the three counties.

Taxable Retail Sales

Taxable retail sales are good indicators of annual spending in the travel-service sectors, since they represent the taxes paid for transactions with consumers. The total taxable retail sales figures include the taxes paid by businesses on raw materials and services. In 2000, the total taxable retail sales for the affected region was approximately $1.5 billion (year 2000 dollars). Madera County accounted for about 58% of total taxable retail sales. Mariposa County accounted for about 8% of total taxable sales. Table III-6 shows total taxable retail sales by county.

^a   Totals may not add up exactly due to rounding.

SOURCES:  Micro IMPLAN Group 1996, adjusted according to U.S. Bureau of Economic Analysis trends in personal income

SOURCE: California State Board of Equalization 2002

County Profiles

Madera County . The central economic activity in Madera County is agriculture, which constitutes nearly one-third of the county’s total employment and over 24% of the county’s economic output (tables III-4 and III-5). The agricultural sector stimulates production in related sectors of the economy, including jobs in food processing, transportation, and wholesale trade.

In Madera County, the construction and mining sector accounts for over 4% of employment and over 7% of total economic output in the county (tables III-4 and III-5).

Mariposa County . Recreation and tourism are major industries in Mariposa County. The county’s primary recreation area/tourist attraction is Yosemite National Park, much of which lies within the county, including the developed areas of Yosemite Valley. Major recreation areas in Mariposa County include Stanislaus National Forest and Sierra National Forest, including the U.S. Forest Service/Bureau of Land Management-managed recreation areas along the Merced River.

The services sector accounts for approximately 40% of employment and 22% of economic output in Mariposa County. Government is also a major economic sector in the county, accounting for 35.4% of employment and 19% of total output. The finance, insurance, and real estate sector accounted for 22% of economic output, although only about 2% of total employment. In Madera County, the construction and mining sector accounts for only 3% of county employment and 11.5% of total economic output in the county (tables III-4 and III-5).

Tuolumne County . A portion of Yosemite National Park is in the southeastern portion of Tuolumne County. The government sector was the largest employer in the county in 2000, accounting for 28.5% of employment and 13% of economic output (tables III-4 and III-5). The services sector accounts for 26.5% of employment and 19.8% of the total economic output. Most of the job growth in Tuolumne County is expected in the services, retail trade, construction, and manufacturing sectors. The services sector is expected to create the greatest number of new jobs, reflecting an increased demand for business, health, personal, and hospitality services.

In Tuolumne County, the construction and mining sector accounts for nearly 6% of county employment and 12.5% of total output in the county (tables III-4, and III-5).

^[1] Biodiversity, or biological diversity, is generally accepted to include genetic diversity within species, species diversity, and a full range of biological community types. The concept is that a landscape is healthy with it includes stable populations of native species that are well distributed across the landscape.